1. Field of Invention
The present invention relates to an apparatus for controlling noise of a vehicle body, and more particularly, to an apparatus for controlling noise of a vehicle body which can differently tune sound quality of noise of a vehicle body, which is generated during driving of a vehicle, according to acceleration and deceleration of a vehicle.
2. Background Art
In general, the structure of a vehicle body includes side frames disposed along opposite sides of a vehicle, and several cross members for transversely connecting the side frames to each other. There is one cross member installed in the vehicle body to support a transmission among the several cross members. This is called a transmission mounting cross member. Further, opposite ends of the transmission mounting cross member are fixed to the side frames.
FIG. 1 is a bottom view showing a state of mounting a transmission to a cross member. As shown in FIG. 1, the transmission mounting cross member (hereinafter, referred to as ‘cross member’) 20 is installed to transversely connect the side frames 10 at opposite lower sides of a vehicle to each other, and the transmission 2 is supported by the cross member 20.
In this case, a mounting unit is installed at an upper side of the cross member 20 and the transmission 2 is mounted to the mounting unit, so that the mounting unit connects the transmission 2 to the cross member 20. In addition, a bush for preventing vibration, which is generated from the transmission and is transferred to the vehicle body, is conventionally mounted between the mounting unit and the transmission.
Meanwhile, noise is generated during driving of a vehicle while the vehicle body including the cross member is vibrating. Thus, the noise is input into a driver seat to cause a driver to feel uncomfortable.
Therefore, a technology for reducing noise of a vehicle body has been required, and noise generated due to the cross member may be reduced by reinforcing strength of the cross member.
Thus, a reinforcement member is installed to increase the strength of the cross member for the purpose of reducing the noise. FIG. 2 is a sectional view showing a state of installing a reinforcement member. As shown in FIG. 2, the reinforcement member 30 as well as the cross member 20 is installed to connect a left side and a right side of side frames to each other. When the reinforcement member 30 is installed, noise may be reduced by using a vibration characteristic of the cross member 20.
If the strength of the cross member is not reinforced, rumble noise (noise such as “doo doo doo” or “vroom”) is generated so that the driver may be made to feel uncomfortable. However, if the strength of the cross member is reinforced by installing the reinforcement member, the noise generated due to the cross member may be reduced.
However, in the case of a technology of simply installing the reinforcement member, when taking into consideration that there exists a difference in the driver-preferable sound qualities of the sounds generated from vehicles, it is difficult to meet a sound characteristic that satisfies the drivers in a certain area.
For example, regarding European-preferable sound characteristic, European-preferable sound characteristic during an acceleration period is different from that during a deceleration period. A silent sound quality is required during the deceleration and a dynamic sound quality is required during the acceleration.
That is, the rumble noise generated when the strength of the cross member is not reinforced may become European-preferable dynamic noise during the acceleration. However, European prefers the silent sound quality which minimizes the noise generation, during the deceleration.
Therefore, it is necessary to specialize the sound characteristic according to areas by considering differences in a driving characteristic, a road condition, and a driver taste. In particular, a sound control technology, which can implement a dynamic sound quality during the acceleration of the vehicle and a silent sound quality during the deceleration of the vehicle according to European-preferable sound characteristic, is required.
When the reinforcement member is not installed, the rumble noise generated during the acceleration may become European-preferable dynamic noise. However, the noise due to the cross member is generated even during the deceleration, so that a driver feels uncomfortable.
In addition, when the reinforcement member 30 is installed as shown in FIG. 2, since the noise is fully removed regardless of the acceleration and deceleration of a vehicle as the strength of the cross member 20 is increased, the driver-preferable sound quality is not satisfied (it is impossible to implement the dynamic noise during the acceleration and the noise is too silent in both cases of acceleration and deceleration due to the installation of the reinforcement member).
Thus, there is a need to provide a technology capable of differently tuning the sound quality according to the acceleration and deceleration of a vehicle by using the cross member.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.